So…What Do I Roll?
Always include base Level in Recovery rolls, but not much else will count. Being a Warrior doesn't teach you to heal faster! What does count is Boosts from Healers providing care, but those do not stack. Additional Healers may try to Boost their senior member so that their roll is better, but only one bonus may be applied for medical care (though other rolls might usefully reduce relevant situational Hindrances.)
Recovery rolls are expected to include the penalties of accumulated Injury.
GMs who want a harsher game can include active Complications. For a lighter game, don't include Harm penalties in recovery rolls at all. Including unclassified Harm in the rolls to determine how much was Injury will make a game grimmer and deadlier, while leaving it out is more cinematic. If adding a second roll for armor, they don't have to use the same sets of modifiers…